


My Soul is Yours

by tsumekakusu



Series: 100 Days of AUs [12]
Category: Haikyuu!!
Genre: Alternate Universe - Soulmates, Angst with a Happy Ending, First years to Third years, Flashbacks, Fluff, Lots of dialogue, M/M, Slice of Life, minor manga spoilers
Language: English
Status: Completed
Published: 2020-06-05
Updated: 2020-06-05
Packaged: 2021-03-03 21:47:22
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,646
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24552610
Author URL: https://archiveofourown.org/users/tsumekakusu/pseuds/tsumekakusu
Summary: “I don’t want a soulmate (if that person isn’t you).”
Relationships: Hinata Shouyou/Kageyama Tobio, Minor or Background Relationship(s), Tsukishima Kei/Yamaguchi Tadashi
Series: 100 Days of AUs [12]
Series URL: https://archiveofourown.org/series/1589305
Comments: 2
Kudos: 161





	My Soul is Yours

**Author's Note:**

> Prompts: clear/invisible, nostalgia, salt (aka loads of denial)  
> This follows the boys from the middle of their first year at Karasuno to the middle of third year. The POV changes between Tadashi and Kei, so please let me know if it’s too confusing. Happy reading!! ^o^

He looks at himself in the mirror, holding back tears when he finds nothing.

No doodles. No words of encouragement. Nothing. 

He’s been checking every day for a sign. Even an accidental squiggle of pen on his arm- A small smiley face on his hand-  _ Anything-  _ But there’s nothing. 

He’s scared to admit it, but he knows. 

_ I don’t have a soulmate.  _

He pulls his shirt on and falls face first on his bed. He’s tempted to write a message on his arm. A simple, ‘Are you doing okay?’ or ‘How are you?’ But-

_ What if no one writes back?  _

He rolls over until he’s laying on his side, staring at the glowing crescent moon and stars covering his wall. The libra constellation takes up half of the wall, reminding him of a flying house. 

_ It’s a weighing scale. _ Kei’s voice fills his mind. He smiles. 

_ No, it’s a flying house, since it makes me feel safe. Just like you do.  _

He remembers his friend quickly turning to hide his blush. _ “Then scorpius is a tether.” _

_ “Why?” _

_ “Because it grounds me back to Earth.”  _

~~~~~~~~~~

“Hey Tsukki, can I draw on your hand?” 

“No.”

“Why not?” He smiles innocently at his best friend’s narrowed gaze. 

“Because I don’t want-”

“To know who your soulmate is. I know,” Tadashi smiles, dropping his chin on his desk. “But what if it’s invisible ink?” 

Kei raises an eyebrow. 

“It’s really popular right now. Look!” Tadashi pulls out a seemingly innocent pen with a small flashlight attached on the cap. 

Kei rolls his eyes. “There’s no way it’s completely invisible, and there’s no point-”

“Woah, Yamaguchi, you got one of those, too?!” Sh ō y ō ’s shout fills the room. 

“Why are you here?” Kei demands, standing from his seat.

“Daichi-san told me to tell you that practice got cancelled. They’re doing repairs in the gym again,” Sh ōyō pouts. 

Kei smirks. “Then we can-” 

“Wanna join us for practice at the park?”  Sh ō y ō cuts him off, eyes pleading towards Tadashi. 

Tadashi sneaks a glance at Kei and holds back a smile.  _ Is he sulking?  _

“Sure,” Tadashi replies, ignoring his childhood friend’s annoyed look. “But I might have to leave early since I promised to meet up with Shimada-san later tonight.” 

Kei scowls. 

“So, have you tried out the pen yet?”  Sh ō y ō asks, oblivious to Kei’s anger. 

“Nope,” Tadashi waves it in the air. 

“Why not?”

“Because  _ someone  _ won’t let me draw on his hand.”

“Oh, come on, Tsukishima! It’s not like anyone’s gonna see it anyways! And it’s like a secret message only  _ you  _ can see!”  Sh ō y ō exclaims, grabbing Tadashi’s pen. He goes to write something on Kei’s hand, but Kei quickly pulls his arms behind his back. 

“Why do you even need to write on my hand?” 

“Because I want to?” 

“What are you guys doing?” Tobio sounds bored as he walks over to them. 

“Trying to write on Tsukishima’s hand,”  Sh ō y ō grins as he aims the pen at Kei’s bicep. 

“Why? If he doesn’t want to know who his soulmate is, then it’s his choice,” Tobio deadpans. 

“Yeah, but-” 

Tobio cups a hand around his soulmate’s ear, whispering, “He might not have a soulmate.” 

“Oh.”  Sh ō y ō looks nervous as he caps the pen and puts it on Tadashi’s desk. “My bad.” 

Kei sighs. He lays his hand out, palm down on his desk. 

Sh ō y ō grins. 

“Not you,” Kei mutters, glancing at Tadashi. 

He smiles nervously. “Are you sure?” 

Kei nods. 

Tadashi carefully picks up the pen and uncaps it. His hands are shaking as he draws a lopsided smiley face on Kei’s pinkie knuckle. 

Sh ō y ō peeks over Tadashi’s shoulder with a frown. “Why did you draw it there? And you should’ve drawn a bigger one!” 

Tadashi smiles at his friend. “I just wanted to try out my pen,” he laughs, recapping it. He uses the flashlight to check his work,  _ yup, definitely lopsided,  _ before dropping it back in his bag. 

“Wait, can I borrow it for a second?” 

“Sure.” He digs through his bag and hands  Sh ō y ō his pen. 

“Awesome!” 

He smiles as  the small bundle of sunshine drags his soulmate back to their classroom to test out the ‘super awesome invisible pen.’

~~~~~~~~~~

He doesn’t get his pen back until after practice. 

“Sorry,” Sh ō y ō hands him the thoroughly used writing device. “I think I used up all the ink.” 

“It’s okay,” Tadashi smiles, already knowing that would happen. “I’m glad you had fun with it.” 

“YEah!!”  Sh ō y ō bounces up and down. “I’m gonna buy Tobio one so we can write secret notes to each other!!” 

Something tightens in Tadashi’s chest, but he continues smiling. “Nice!” 

“And I promise I’ll buy you another one!” 

“Cool, thanks!”

~~~~~~~~~~

He’s going through his messy backpack, when he accidentally grabs the invisible ink pen instead of his mechanical pencil. 

He tests the light and smiles.  _ At least that works.  _ He uncaps the pen and draws a small heart in the middle of his hand. He shines the light on it and frowns.  _ Yeah, it’s out of ink. Maybe I’ll-  _

He drops the cap. 

_ No. No no no- _

He picks up the flashlight with shaking hands.  _ No. There’s no way...  _

He shines the light over his pinkie knuckle, revealing a lopsided smiley face.  _ No.  _

_ He’s- Tsukki’s my-  _

_ No. He doesn’t want a soulmate. He doesn’t want  _ me. 

He remembers the conversation they had last year, about soulmates and relationships in general. 

_ “Why do you never write on your hand?” Tadashi gazed up at the stars, before peeking over at his best friend.  _

_ “Because I don’t want a soulmate,” Kei answered with a scowl.  _

_ “Why not?”  _

_ “Because-” he let out a breath, “Just because you’re soulmates doesn’t mean you’ll end up together. And I don’t want to be in a relationship right now.”  _

_ “Oh. Okay.”  _

He feels tears threatening to spill down his cheeks.  _ He doesn’t want me. He never wanted me.  _ He falls back onto his bed and curls into himself.  _ Why? Why is my life always like this?  _

He closes his eyes, letting the tears finally fall on his sheets. 

~~~~~~~~~~

They’re second year’s now. But nothing changes. No, he’d be lying if he said  _ nothing  _ changed. 

It’s different without the third years. Chikara-senpai’s leadership is steady and strong. Tanaka-senpai’s support is rowdy, but reassuring. The new first years are full of potential. He’s leveled up from being just a pinch server to actually playing in games as a middle blocker. (It helps to have gained a few centimeters during his late summer growth spurt.)

But his relationship with Kei stays the same. Granted, Kei had slowly started becoming more comfortable with physical touches after their whole ‘ _ What more do you need than pride _ ’ shake down, but they stayed the same. Childhood best friends. Nothing more, nothing less. 

And Tadashi’s happy with that. He’s seen what happens when soulmates find each other too early. He’s seen what happens when people assume, and plot, and overanalyze. 

He’s far past that stage. 

_ Tsukki’s my soulmate.  _ He’d gotten over the denial phase rather quickly.  _ But he’s not ready to know yet. I’m not ready to tell him yet.  _ He isn’t sure if Kei will ever change his mind about soulmates, but he’s willing to wait. 

~~~~~~~~~~

He’s never wanted a soulmate. He doesn’t like the idea of something as fickle as  _ fate  _ deciding who he’ll end up with. 

_ He  _ gets to decide who he loves.  _ He  _ gets to decide his own future, not some weird phenomenon that barely even makes sense. 

“Tsukki, we’re going to be late for practice!” Tadashi lays a gentle hand on his shoulder. 

Kei nods. “Let me finish packing.” He slides his books into his bag and swings it over his shoulder. His lips twitch when he feels Tadashi’s hand slide down and squeeze his arm. “Let’s go.” 

Tadashi leads him by the arm to the gym. 

~~~~~~~~~~

“Sorry Tsukki, I need to ask my math teacher a question. I’ll be right behind you!” Tadashi runs out of the classroom. 

Kei watches him go with a frown. Tadashi  _ hates  _ math. Why would he willingly want to talk more about math? 

He follows his friend’s footsteps to the path leading outside. He blanches. 

_ Of course.  _ He hides behind a tree as he witnesses a shy girl holding out a pink envelope to his best friend. 

“I’m sorry,” Tadashi sounds genuinely apologetic as he shakes his head. 

“I- We both don’t have soulmates, and I-” 

“Just because you might not have a soulmate, doesn’t mean you should settle for anything less,” Tadashi mutters, stepping forward to lay a gentle hand on the girl’s shoulder. 

Kei’s whole body stiffens. He knows he shouldn’t be eavesdropping, but he can’t stop staring at Tadashi’s hand on the girl’s shoulder. 

“That’s not why I’m...” the girl trails off, before she sighs softly. “I just thought... I’m genuinely interested in you,” she replies honestly. 

“I’m honored to have your interest,” Tadashi smiles. “But I already have someone I like.” 

“You do?” she looks up to meet Tadashi’s amused gaze. 

“I do.” 

Kei panics.  _ Who? What? When?  _ He slowly walks back to the classroom and sinks into his chair.  _ What... the what? He- Tadashi- Why-  _

“You okay, Tsukki? I thought you were already at practice,” Tadashi smiles down at him. 

Kei nods distractedly. 

“You sure? Are you feeling sick?” Tadashi peers into his face. 

“I’m fine.” Kei pushes Tadashi’s forehead back, feeling a strange tingle in his fingers where their skin touched. 

“Okay,” Tadashi mutters. He grins as he grabs both their bags and jogs out of the room. 

Kei’s lips twitch into a small smile.  _ Nothing’s going to change. I won’t let it.  _

~~~~~~~~~~

Everything changes. 

Every little touch, every secret smile, every small lie,  _ there’s no way he needs to meet with his math teacher twice a week,  _ feels like torture. He’s used to killing all emotion and shoving it deep within himself, but he isn’t used to the panicked thoughts overtaking his mind as he wonders who’s stolen Tadashi’s heart. 

_ What if he leaves me?  _

It’s a constant thought in the back of his mind. Their relationship has always been a push-and-pull, with Tadashi pushing more than pulling. Maybe it’s Kei’s turn to give back. 

“Yamaguchi, are you free this Saturday?”

“Yeah, why?” 

“My brother bought me Animal Crossing, but I need advice on how to decorate my house.”

“ _ You’re _ asking me for advice on  _ interior design? _ ” Tadashi laughs.

“We decorated our rooms together,” Kei reasons. “Do you not want to-”

“No, I’ll go! Or I mean, I’ll help you decorate your house, yeah,” Tadashi grins. “Only if you let me add stars to your room, though.” 

“Scorpius?” Kei asks. 

“Yeah. And once I save up enough money to buy the game, we’ll add Libra to my room,” Tadashi promises. 

Kei nods. He feels a familiar feeling bloom within his chest as he continues to nod along to his friend’s excited suggestions.

~~~~~~~~~~

They’re sleeping side-by-side, Kei chose to sleep next to Tadashi even though his back always hurts after sleeping on a futon. 

“Why... Nevermind,” Tadashi mutters, hiding his face in his pillow. 

Kei hums, rolling over to face his friend. 

Tadashi peeks up at him with a curious look. “Why... do you not want to know who...” he trails off again at Kei’s narrowed gaze. 

_ Because I’m in love with you.  _

“Because I don’t want to be in a relationship during high school.”

_ Because I’m afraid I don’t have a soulmate. Because I’m afraid my soulmate isn’t  _ you. 

“Oh. Okay.” Tadashi rolls over until his back faces Kei. 

He wants to wrap his arms around him. He wants to pull him against his chest and tell him everything he’s been holding back since he fell in love with him. But he doesn’t.

~~~~~~~~~~

“So you still don’t know who your soulmate is?” Tobio casually asks as they change for practice.

Kei glares at him. 

“Have you ever written anything on yourself?” 

Kei shakes his head. 

“Then you shouldn’t be afraid of not having a soulmate. Here,” Tobio hands him a pen. “Draw something on your hand. See if your soulmate writes back.” 

Kei scowls. 

Tobio rolls his eyes. “It’s not the end of the world if no one answers.”

“Not very reassuring coming from someone covered in drawings,” Kei snickers at Tobio’s blush. “I thought shorty bought invisible markers for you to use.” 

“We ran out,” Tobio mutters, ignoring Kei as his smirk widens. “We’re getting some more after practice today.” 

“You still owe Tadashi one,” Kei deadpans. 

Tobio smirks. “You call him Tadashi now?” 

Kei scowls. “Shut up.” 

Tobio tilts his head. “Are you sure you don’t know who your soulmate is?” 

Kei nods. 

Tobio gives him a calculating glare. 

“What?” 

“Nothing.” Tobio gives him one last look before heading towards the gym.

~~~~~~~~~~

He stares at the pen in his locker, willing it to disappear. 

“Oh, you got one too?” Tadashi mutters, peeking over his shoulder. 

Kei holds back a grimace as he pockets the pen. 

“You’re not gonna try it out?” Tadashi asks, twirling his own pen around his fingers. 

Kei shakes his head. 

Tadashi frowns. “You don’t have to use it to draw on yourself, you know. We could pass secret notes during class!” he exclaims, waving the pen over his head. 

“Yeah, and possibly get it read by shorty and grumpy over there,” he motions toward the couple arguing in the corner of the locker room. 

“They’re not in our class,” Tadashi chuckles, draping an arm over Kei’s shoulders. 

Kei hums. 

“And they can’t keep up with our jokes,” Tadashi grins. 

Kei lets his lips curve into an answering smirk. 

~~~~~~~~~~

_ Tsukki, I’m having second thoughts on being captain.  _

Kei’s eyes widen at the note. He’d realized early on that their notes usually contained things they were too scared to say out loud, but  _ woah, I wasn’t ready for this.  _ He scribbles a quick reply and throws the paper over his shoulder. 

He hears a soft sigh behind him and barely resists the urge to sneak a glance back. 

~~~~~~~~~~

“Why are you having second thoughts?” Kei asks, as soon as they pass the gate. He knows Tadashi has been waiting for this question, and he also knows he’s too impatient to wait for an answer. 

“I just- To be perfectly honest, I wanted  _ you  _ to be captain, Tsukki,” Tadashi admits, meeting Kei’s gaze. 

His eyes widen. “Why would you want me to be captain?” 

“Because you’re always calm even in stressful situations. Because you’ve been a starter since first year. And-” 

“None of that matters,” Kei states, grabbing Tadashi’s shoulder. 

Tadashi stumbles, before leaning into Kei’s touch. 

Kei lets a soft smile bloom across his face. “We wouldn’t have voted for you if we didn’t think you were capable. And it was a unanimous vote, including both Takeda-sensei and the coach.”

“But-”

“I’m still mad Kageyama got vice captain,” Kei cuts him off.

“What? You-” Tadashi holds his stomach as he falls over in laughter. “No way!” 

Kei feigns a scowl. “He’s too stupid to be vice captain.” 

“I- I can’t believe-” Tadashi gasps. “You- ahahahaha-”

“Shut up, Tadashi.”

“S-Sorry Tsukki.”

~~~~~~~~~~

Winter turns to spring, and another graduation passes. He grudgingly returns every hug and holds back a smirk when Tadashi hides his tears against Kei’s chest. He gently wraps an arm around his shoulders and guides him toward the nearest bench. 

“Sorry Tsukki, I didn’t mean to break down in the middle of the field,” Tadashi tries to quickly wipe his tears. 

“It’s okay,” Kei whispers. He pulls Tadashi’s face back towards his chest. He holds back a grin as Tadashi lets his cheek get squished against Kei’s collarbone.

“I can’t believe we’re gonna be third years,” Tadashi whispers. 

Kei rests his head on top of Tadashi’s. “Yeah.” 

“I’m still scared about being captain.”

Kei curls an arm around Tadashi’s back. He rubs up and down along his spine, smirking as the tension slowly leaves his body.

“But I’m also excited. I wonder if any first years are interested in being setter?” 

“That’s  _ if  _ we get any first years.” 

“I know we didn’t win Nationals, but we beat Fukurodani,” Tadashi grins. “And Nekoma too!”

“We beat Nekoma last year,” Kei scoffs. 

“I know but- Anyways, I’m excited! And a little scared. But mostly excited,” Tadashi lets out a long breath as he sinks into Kei’s arms. 

_ Me too.  _ Kei tightens his arms around Tadashi’s back, smiling as he feels strong arms wrap around his waist. 

~~~~~~~~~~

It was completely by accident. 

They were partners for a science experiment, a completely self-conducted project from start to finish. Tadashi had jokingly suggested trying to make their own invisible ink. Kei had hesitated at first, but agreed on the account that they used it to get revenge on Tobio and  Sh ō y ō for their prank gone wrong. (Kei still had remnants of blue that he couldn’t wash out, although Tadashi with red hair had been almost too much for him. He’s sure the rest of the school agrees.)

“How are we gonna get them back?” Tadashi asks, absentmindedly doodling a heart on his hand. 

He’s never seen Tadashi write anything on his hand, but it seemed almost natural for Tadashi to draw a small heart on his pinkie knuckle. He feels a weird sense of deja vu, but ignores it in favor of smirking evilly. “I’ll think of something.” 

“I’m sure you will,” Tadashi smirks back. He flickers the light over his hand, smiling at the small heart on it. 

Kei snickers. “What if we scare them into thinking the locker room’s haunted? Or maybe the gym?” 

“How are you gonna do that?” 

“We’ll draw volleyballs with skulls on their hands. Then-” He stops when he shines the light on his hand. 

A small blue heart appears, covering the scar on his pinkie knuckle.

Tadashi’s smile disappears. 

“You-” 

Tadashi sprints out of the classroom. 

_ Shit.  _ Kei runs after him, ignoring the startled stares as they sprint through the empty hallways. 

They’re almost to the gate, when a large crow flies right in front of Tadashi. Kei takes that moment of hesitation to pull Tadashi back into his arms. 

Tadashi struggles against his hold, but gives up when he feels a soft kiss against his ear. “Tsukki, what-”

“You’re my soulmate,” Kei breathes out, revelling in Tadashi’s shiver. “You’re  _ my soulmate.”  _

“I thought you didn’t-”

“I don’t- Or, I didn’t,” Kei admits. “But that was before- That was because I fell in love with you,” he whispers the last part, tightening his arms around Tadashi’s waist. 

“I- what?” Tadashi turns in his embrace, until their faces are only a few centimeters away. 

“I don’t need fate to tell me who I love. Or who to fall in love with,” Kei mutters, hiding his face in Tadashi’s neck. 

“That- Makes sense. I- yeah,” Tadashi whispers, bringing his arms around Kei’s neck. “But wow- that was late.” 

“You’re the one who didn’t tell me you’re my soulmate,” Kei argues, poking his nose against Tadashi’s neck. 

Tadashi giggles, before he tenses slightly. “I thought you didn’t want me.” 

Kei scowls. “Never. That would never happen.” 

“Are you sure?” Tadashi mutters. “I know you don’t like being tied down and-” 

“Don’t,” Kei whispers, shaking his head. “You need to stop overthinking things. And yes, not everything is solved just because I found out you’re my soulmate, but- wait-” 

“Hmmm?” Tadashi hums against his chest. 

“You have someone you like. Who is it?” Kei pulls back and narrows his eyes at him. 

“Really? You’re asking me that now?” Tadashi chuckles. “And how’d you find out I have someone I like, hmmm?” 

Kei avoids his knowing smile. “Hinata told me.” 

“Okay,” Tadashi grins, before laughing softly. “Really? You’re really going to make me say it?” 

Kei gives him an annoyed stare. 

“I like you, Kei,” Tadashi murmurs, revelling in Kei’s look of shock. “I can’t believe you’re surprised right now. I’ve been in love with you for  _ five years _ , Kei.”

“How long did you know we’re soulmates?” Kei asks. 

“Does it matter?”    
Kei looks away. 

“I found out middle of first year, so... a little over two years now?” Tadashi mutters. 

Kei frowns. “You’ve known for two years.”

“Yeah, and you weren’t interested in soulmates or being in a relationship, so look where that got us,” Tadashi laughs, patting Kei’s chest. 

“I’m so-”

“As much as I’d like to hear Tsukishima apologize, I think it would be better if you took this somewhere private?” Tobio’s voice interrupts them. 

Tadashi jumps and hides his face in Kei’s chest. Kei hugs Tadashi’s head and glares at the curious eyes watching them from across the field. 

“Thanks, Tobio,” Tadashi mutters, waving to his friend as Kei leads them toward the volleyball locker room.

~~~~~~~~~~

It’s almost like nothing’s changed. They still walk together to school and write secret notes to each other during class. They meet up on weekends to study and play games. They text constantly and send each other snarky memes. 

But now they hold hands on their way to school, and sometimes during lunch when Kei thinks no one’s looking. They draw hearts and secret notes on their hands and arms, until they’re covered in invisible doodles. Their first kiss happens on a late night out under the stars, and it quickly leads to stolen kisses in the locker room, or any empty room they can find. Tadashi’s texts are filled with hearts and hugs, and he soars when Kei replies with every shy heart sticker. 

“Hey, Kei?” Tadashi whispers, kissing his boyfriend’s cheek. 

Kei hums as he nuzzles Tadashi’s collarbone. 

“I love you.” He smiles at the grin against his neck. 

“I love you too.”

**Author's Note:**

> This was written in one sitting as a comfort fic <3 It's been a long few weeks, but TsukkiYama can always make my day better, and I hope it did for you too! 
> 
> (Disclaimer: I do not own Haikyuu!! or any of the characters! Thanks so much for reading!!! ^o^)


End file.
